A carbon-nitrogen ratio adaptive side-flow sewage treatment system and sludge reduction method

Abstract

The present application relates to sewage treatment technical field, specifically disclose a kind of carbon nitrogen ratio self-adaptive side stream sewage treatment system and method.System includes main stream reactor, side stream reactor, monitoring unit, intelligent control unit, reflux path switching device and inoculant targeted dosing system.Through real-time monitoring of influent C / N, intelligently switch the operation mode, parameter, inoculant dosing strategy and effluent reflux path of ASSR: low C / N, start latent growth mode, effluent back anaerobic zone, through "cracking-latent growth" mechanism preferentially carbon supplement and synergistic reduction;High C / N, start metabolic remodeling mode, effluent back aerobic front end, through "energy decoupling" mechanism to realize fundamental reduction and strengthen denitrification and phosphorus removal.The present application is through "mode-parameter-inoculant-path" linkage control, solve ASSR process mechanism and water quality mismatch problem, realize carbon flow / electron flow optimal distribution and sludge efficient reduction.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to an intelligent control system and method for activated sludge process, specifically a side-flow wastewater treatment system with adaptive carbon-nitrogen ratio and a sludge reduction method. Background Technology

[0002] Anaerobic side-flow reactor (ASSR) technology is an effective means of achieving in-situ sludge reduction in wastewater treatment plants. However, existing technologies have significant drawbacks: they employ a single, fixed operating mode and return path, making them unable to respond to changes in influent water quality. This leads to insufficient carbon sources and low nitrogen and phosphorus removal efficiency at low C / N ratios; and high sludge production and sludge bulking at high C / N ratios. The core issue lies in the failure to precisely match the different reduction mechanisms of ASSR (hydrolysis acidification and metabolic remodeling) with the influent water quality (C / N ratio) and to optimize its return path to achieve optimal carbon flow distribution.

[0003] Treatment processes for wastewater with different carbon-to-nitrogen ratios generally include the AAO (Anaerobic-Anaerobic) process and the A / O (Anaerobic-Oxygen) process. These traditional processes have significant drawbacks when treating wastewater with large fluctuations in the carbon-to-nitrogen ratio (C / N), mainly in the following aspects:

[0004] First, the carbon-nitrogen ratio adaptability is poor: low C / N (C / N<5) wastewater requires external carbon addition, increasing operating costs; high C / N (C / N>5) easily causes sludge bulking and poor system stability.

[0005] Second, the sludge reduction efficiency is low: the traditional process that relies on endogenous respiration has a sludge reduction rate of less than 30%, and functional bacteria are easily inactivated.

[0006] Third, the side-flow unit has a single function: existing side-flow reactors are mostly used for sludge thickening or methanation, and have not formed a synergistic control network with the mainstream process.

[0007] Fourth, temperature sensitivity: low temperatures can inhibit microbial activity, while high temperatures may trigger nonspecific cell lysis, and seasonal fluctuations exacerbate the difficulty of regulation. Summary of the Invention

[0008] To address the aforementioned technical challenges, this invention provides a dynamic synergistic control system. This system utilizes a dual-function switching mechanism between hydrolysis acidification and microbial screening in a side-flow reactor, targeted microbial agent dosing, optimized reflux path, and a low-temperature heating device to resolve the coupling issue between C / N fluctuations and temperature effects. Under low-temperature conditions, the side-flow reactor activates the heating device to enhance hydrolysis efficiency for low C / N ratios and maintain microbial community enrichment stability for high C / N ratios, achieving stable operation year-round. Through dynamic parameter control of the side-flow reactor, targeted acclimatization and dosing of functional microorganisms, and optimized reflux path, the system achieves broad-spectrum adaptability for C / N < 4.5, 4.5 ≤ C / N ≤ 6, and C / N > 6, simultaneously improving pollutant removal efficiency and sludge reduction rate. It is suitable for high / low C / N ratio scenarios such as municipal wastewater, food wastewater, and chemical wastewater.

[0009] The objective of this invention can be achieved through the following technical solutions:

[0010] In a first aspect, the present invention provides a carbon-to-nitrogen ratio adaptive side-flow wastewater treatment system, comprising:

[0011] Mainstream reactor, side-flow anaerobic reactor (ASSR), online monitoring unit, intelligent control unit, reflux path switching device, and targeted dosing system for microbial agents;

[0012] The mainstream reactor includes an anaerobic zone, an anoxic zone, and an aerobic zone, or a mainstream A / O reactor with anaerobic and aerobic sections connected in series, and an integrated DO controller.

[0013] The side-flow anaerobic reactor is equipped with HRT (hydraulic retention time) or SRT (sludge retention time), temperature and pH dynamic adjustment devices, and a stirring unit. The side-flow anaerobic reactor is connected to the main flow reactor via a sludge return pump.

[0014] The online monitoring unit is used to detect the COD and TN concentrations of the influent in real time and calculate the C / N ratio, or to integrate an online C / N detector;

[0015] The reflux path switching device includes a controllable valve and a corresponding delivery pipeline, which selectively refluxes the effluent from the side-flow anaerobic reactor back to the front end of the anaerobic or aerobic zone of the main flow reactor.

[0016] The targeted dosing system for microbial agents includes a freeze-dried microbial agent library, enzymes, and a compound protectant.

[0017] The intelligent control unit is configured to: control the side-flow anaerobic reactor to switch between at least two operating modes based on the influent C / N ratio detected by the online monitoring unit; control the operating parameters of the side-flow anaerobic reactor; control the selective addition of microbial agents and / or enzymes by the microbial agent targeted dosing system; and control the reflux path switching device to selectively reflux the effluent from the side-flow anaerobic reactor back to the anaerobic or aerobic zone of the main flow reactor.

[0018] Furthermore, the bacterial agent is protected by a composite protectant, and its activity period at room temperature is ≥12 months. The freeze-dried bacterial agent library contains endogenous carbon source metabolic bacteria; the endogenous carbon source metabolic bacteria is Candidatus Accumulibacter; the composite protectant is composed of trehalose and nano-sized kaolin in a mass ratio of 1:2; and the enzymes include proteases and glycosidases.

[0019] Furthermore, the operating mode includes:

[0020] Latent growth mode: When the influent C / N ratio is less than 4.5, the following operating mode is activated: the side-flow anaerobic reactor is controlled to operate with the first set of parameters, the enzyme is added to the side-flow anaerobic reactor by the targeted dosing system of the microbial agent, and the effluent from the side-flow anaerobic reactor (ASSR) is controlled to be returned to the anaerobic zone of the main reactor.

[0021] Metabolic remodeling mode: When the influent C / N ratio is greater than 6, the following operating mode is activated: the side-flow anaerobic reactor is controlled to operate with the second set of parameters, the microbial agent targeted dosing system is controlled to add internal carbon source metabolic bacteria to the side-flow anaerobic reactor, and the effluent from the side-flow anaerobic reactor (ASSR) is controlled to be returned to the aerobic zone of the main reactor.

[0022] Energy-saving mode: Activate energy-saving mode when influent C / N ratio is 4.5 ≤ C / N ≤ 6. For the conservative energy-saving mode, within this range, the system defaults to a mild version of the latent growth mode. A shorter HRT (e.g., 6-8 hours) is used, but high-temperature heating is not performed (maintaining ambient temperature or slightly increasing the temperature to 30-35℃), and the pH is allowed to develop naturally (usually between 6.5 and 7.0). At this C / N ratio, although carbon sources are not abundant, they are still the main problem for most municipal wastewater treatment in my country. Using a mild, short-duration ASSR can generate a suitable amount of VFA to assist in nitrogen and phosphorus removal, while its own latent growth effect also brings a certain reduction effect. Avoiding high-temperature heating can significantly reduce energy consumption, making operation within this range the most economical. This is a robust and energy-saving strategy.

[0023] For trend prediction switching, the intelligent control unit not only monitors the instantaneous C / N value but also analyzes its changing trend (such as the rate of increase or decrease over the past 2 hours). If the C / N value is rapidly increasing and approaching the second threshold, it gradually shifts towards the parameters of the metabolic remodeling mode in advance; if the C / N value is rapidly decreasing and approaching the first threshold, it shifts towards the parameters of the latent growth mode in advance. This makes the system switching smoother, reduces mode oscillations caused by water quality fluctuations, and improves system stability.

[0024] Furthermore, the first set of parameters includes: hydraulic retention time (HRT) 4-12 hours, temperature 50-60℃, pH 5.0-6.0; the second set of parameters includes: sludge retention time (SRT) 5-15 days, temperature 25-35℃, pH 7.0-7.8.

[0025] Furthermore, the intelligent control unit is also configured to: activate the heating device of the side-flow anaerobic reactor when the ambient temperature is <15℃, raise the temperature to 50-60℃ in the latent growth mode, and maintain the temperature at 25-35℃ in the metabolic remodeling mode.

[0026] Furthermore, the intelligent control unit is also configured to: in the latent growth mode, adjust the DO in the aerobic section of the mainstream reactor to 0.1-0.5 mg / L to inhibit the proliferation of heterotrophic bacteria and promote the dominance of amino acid metabolizing bacteria; in the metabolic remodeling mode, adjust the DO in the anaerobic section of the mainstream reactor to 0.1-0.3 mg / L and the DO in the aerobic section to 1.5-3.0 mg / L to enhance the coupling of internal carbon source oxidation and denitrification.

[0027] Secondly, the present invention provides a method for sludge reduction using the above-described system, comprising the following steps:

[0028] (1) Monitor the influent water quality in real time through an online monitoring unit and calculate the carbon (C / N) ratio;

[0029] (2) If C / N is lower than the first threshold, the side-flow anaerobic reactor is controlled to operate in the latent growth mode, and the microbial agent targeted dosing system is controlled to add enzymes and / or amino acid metabolizing bacteria to the side-flow anaerobic reactor, and the effluent from the side-flow anaerobic reactor is returned to the anaerobic zone of the main reactor.

[0030] The mechanism of short-term ASSR (latent growth pattern) reduction is as follows:

[0031] The core of this model is "cell lysis (Lysis) + cryptic growth (Cryptic Growth)," which is essentially "carbon source cycling."

[0032] Side-flow lysis: In a side-flow reactor, a short heat transfer time (HRT) (4-12 h), high temperature (50-60 °C), and acidic environment (pH 5.0-6.0) create excellent conditions for hydrolysis and acidification. High temperature effectively disrupts the sludge floc structure and lyses microbial cell walls and membranes. The acidic environment strongly inhibits the activity of methanogenic bacteria that consume volatile fatty acids (VFAs) while activating the activity of hydrolytic enzymes and acidifying bacteria. As a result, a large number of microbial cells are lysed, and cell contents (proteins, polysaccharides, lipids, nucleic acids, etc.) and extracellular polymeric substances (EPS) are released into the water.

[0033] Sidestream hydrolysis and acidogenesis: The released large organic molecules are degraded into smaller molecules (such as amino acids, monosaccharides, and long-chain fatty acids) by hydrolytic enzymes (in this invention, proteases and glycosidases can be added to enhance this process). These smaller molecules are further utilized by fermenting and acid-producing bacteria. The metabolic end products are mainly volatile fatty acids (VFAs, such as acetic acid and propionic acid) and small amounts of alcohols, ketones, H2, and CO2.

[0034] Mainstream Cryptic Growth: The VFA-rich sidestream mixed liquor is returned to the anaerobic zone of the mainstream reactor. VFA, as a high-quality carbon source, is preferentially utilized by polyphosphate-accumulating organisms (PAOs) and denitrifying bacteria, significantly enhancing biological phosphorus and nitrogen removal efficiency (solving the core contradiction of low C / N water). Some unused lysate products and VFA are used as substrates by other heterotrophic bacteria in the aerobic zone to synthesize new cellular material; this process is called "cryptic growth." Additionally, the addition of ASSR enhances the hydrolysis and pyrolysis processes of the mainstream sludge, further amplifying the sludge reduction effect brought about by cryptic growth. The essence of sludge reduction is that cryptic growth is a secondary synthesis process with extremely low energy efficiency. Cell lysis already causes energy loss, and secondary synthesis results in further energy loss. Ultimately, the total COD (energy) in the influent is consumed more for generating heat and CO2, rather than for synthesizing new biomass, thus achieving sludge reduction. Sludge reduction is a "byproduct" of the carbon source recovery process.

[0035] (3) If the C / N ratio is higher than the second threshold, the side-flow anaerobic reactor is controlled to operate in metabolic remodeling mode, the microbial agent targeted dosing system is controlled to add internal carbon source metabolic bacteria to the side-flow anaerobic reactor, and the effluent from the side-flow anaerobic reactor is returned to the aerobic zone of the main reactor.

[0036] The mechanism of metabolic remodeling reduction is as follows:

[0037] This environment exerts strong ecological selection pressure, enriching PHA storage bacteria (such as PAOs / GAOs) and promoting the secretion of laccase, peroxidase, and other enzymes through oxidative stress (upregulation of oxyR / soxR genes), catalyzing the synthesis of electron shuttles such as fulvic acid. The core of this reduction model is "metabolic selection pressure + energy uncoupling." The energy allocation strategy of the microbial community is fundamentally reshaped: during the anaerobic period, energy is consumed to synthesize PHA; during the aerobic period, most of the energy generated by PHA oxidation is used to maintain metabolism and phosphorus removal / denitrification, and some electrons are transferred extracellularly through fulvic acid, bypassing the coupled phosphorylation that produces ATP, resulting in energy loss as heat. The total amount of ATP produced per unit of influent COD is reduced, and the proportion used for biosynthesis is significantly decreased, reducing sludge production at the source. Reduction is the direct goal; its essence is a revolution in the "energy economy" model of the microbial society. It provides an immediate environment for the aerobic oxidation of PHA within the functional bacterial community, generating energy for superphosphate uptake; it enables fulvic acid in EPS to work efficiently at the aerobic-anoxic interface, directly transferring electrons from the PHA oxidation process to nitrate (denitrification), significantly enhancing the efficiency of simultaneous nitrification-denitrification (SND) and denitrification phosphorus removal.

[0038] Returning ASSR sludge to the aerobic tank is key to activating the synergistic effect of the entire process: it triggers a violent oxidative stress reaction, significantly enriches electroactive components such as fulvic acid in EPS (fluorescence intensity increased by ~275%), and constructs a highly efficient extracellular electron shuttle network; this allows the PHA electrons stored in the cells to be efficiently and directionally transported to the functional microbial community, thereby achieving a significant reduction in sludge production (>50%) while driving a significant increase in denitrification and phosphorus removal rates (increasing TN and TP removal rates by approximately 15% and 10% respectively compared to traditional processes), ultimately achieving the dual goals of sludge reduction and deep pollutant removal simultaneously.

[0039] The core of this model is "metabolic selection pressure + energy uncoupling", and its essence is "metabolic revolution".

[0040] Ecological Selection Pressure: Placing sludge in a long SRT_SS (5-15 days) and strictly anaerobic environment creates a powerful ecological selection pressure. Common heterotrophic bacteria with short generation times and rapid growth cannot compete in this "starvation" environment and are gradually eliminated. Meanwhile, a group of bacteria with special metabolic strategies—polyhydroxyalkanoate (PHA) storage bacteria (such as polyphosphate-accumulating bacteria PAOs and polysaccharide-accumulating bacteria GAOs)—becomes the dominant flora. Their metabolic pattern is that of a champion of "feast-famine."

[0041] Metabolic Remodeling: Anaerobic Phase ("Feasting" Phase): These bacteria rapidly absorb simple carbon sources such as VFAs from the influent, but do not use them directly for proliferation. Instead, they synthesize PHAs (such as PHB and PHV) at the cost of ATP consumption and store them in their bodies. This is an "investment" process, consuming energy to store carbon sources. Aerobic / Anoxic Phase ("Starvation" Phase): They oxidize and decompose the PHAs stored in their bodies, producing energy (ATP) and reducing power (NADH). This is used to maintain life activities (Maintenance metabolism). It is used to absorb phosphorus (for PAOs) or reduce nitrates (for denitrifying PAOs). Only a very small portion of the energy is used to synthesize new cellular material.

[0042] The essence of energy decoupling and reduction: In traditional metabolism, electron flow (e - ATP is generated from substrates via the respiratory chain and is primarily used for biosynthesis (proliferation). In the metabolism of PHA storage bacteria, the flow of energy (ATP and electrons) is reprogrammed and decoupled: some ATP is "wasted" in PHA synthesis during the anaerobic period (energy investment). Some electrons are transferred during the aerobic period through the decoupled respiratory chain (e.g., bypassing some coupling sites by electron shuttles such as fulvic acid), and energy is dissipated as heat. Ultimately, the total amount of ATP produced per unit mass of influent COD is reduced, and the proportion of ATP used for biosynthesis is significantly decreased. The essence of sludge reduction: the overall metabolic phenotype of the microbial community changes from "maximizing proliferation" to "prioritizing storage and maintenance," cutting off the root cause of sludge production at its source and achieving fundamental and highly efficient sludge reduction.

[0043] (4) If the first threshold ≤ C / N ≤ the second threshold, then the energy-saving mode is activated, and mild parameters (HRT = 6-8 hours, 30-35℃) are used to return the anaerobic fluid to the anaerobic zone.

[0044] The water quality in this range is in a critical state of "neither abundant nor excessive carbon source." Simply "maintaining the current mode" may lead to mode oscillation, while "mixed mode" lacks definition. The smartest strategy is to introduce a third mode—an energy-saving conservative mode—or to use fuzzy control, switching based on trend prediction.

[0045] For the energy-saving conservative mode, within this range, the system defaults to a mild version of the latent growth mode. A shorter HRT (e.g., 6-8 hours) is used, but high-temperature heating is avoided (maintaining room temperature or slightly increasing to 30-35℃), and the pH is allowed to develop naturally (usually between 6.5 and 7.0). At this C / N ratio, although carbon sources are not abundant, they are still the main problem for most municipal wastewater treatment in my country. Using a mild, short-duration ASSR can generate a suitable amount of VFA to assist in nitrogen and phosphorus removal, while its own latent growth effect also contributes to some reduction. Avoiding high-temperature heating significantly reduces energy consumption, making operation within this range economically optimal. This is a robust and energy-saving strategy.

[0046] For trend-based switching, the intelligent control unit not only monitors the instantaneous C / N ratio but also analyzes its changing trend (such as the rate of increase or decrease over the past two hours). If the C / N ratio is rapidly rising and approaching the second threshold, it gradually shifts towards the parameters of the metabolic remodeling mode in advance; if the C / N ratio is rapidly decreasing and approaching the first threshold, it shifts towards the parameters of the carbon source replenishment mode in advance. This makes system switching smoother, reduces mode oscillations caused by water quality fluctuations, and improves system stability. However, this requires more complex algorithms and more reliable water quality prediction models.

[0047] Therefore, if the first threshold ≤ C / N ≤ the second threshold, the intelligent control unit activates the energy-saving conservative mode. The ASSR is controlled to operate with a moderate hydraulic retention time (HRT = 6-8 hours), heating is stopped (maintaining ambient temperature or slightly raising it to 30-35℃, and pH is not actively adjusted). In this mode, the ASSR maintains moderate hydrolysis and acidification functions with low energy consumption, synergistically achieving latent growth and sludge reduction.

[0048] Furthermore, the first threshold value ranges from less than 4.5, and the second threshold value ranges from greater than 6.

[0049] Furthermore, the method also includes the steps of: when the ambient temperature is <15℃, starting the heating device of the side-flow anaerobic reactor, raising the temperature to 50-60℃ in the latent growth mode, and maintaining it at 25-35℃ in the metabolic remodeling mode.

[0050] Furthermore, the method also includes the following steps: in the latent growth mode, controlling the DO in the aerobic section of the mainstream reactor to 0.1–0.5 mg / L to inhibit the proliferation of heterotrophic bacteria and promote the dominance of amino acid metabolizing bacteria; in the metabolic remodeling mode, adjusting the DO in the anaerobic section of the mainstream reactor to 0.1–0.3 mg / L and the DO in the aerobic section to 1.5–3.0 mg / L to enhance the coupling of internal carbon source oxidation and denitrification.

[0051] The principle of sludge reduction in this invention is as follows:

[0052] The two reduction mechanisms of ASSR are fundamentally different, and different reflux paths and microbial agent strategies need to be matched to maximize their effectiveness.

[0053] Latent growth mode (short-term, high-temperature, acidification, enzyme / amino acid metabolizing bacteria): Waste reduction stems from energy loss and latent growth. Returning the waste to the anaerobic zone ensures that the product VFA can be utilized most efficiently by PAOs, thus simultaneously achieving efficient phosphorus removal and waste reduction. The added hydrolytic enzymes enhance the lysing and hydrolysis processes. Furthermore, it accelerates the hydrolysis process of mainstream POM, further enhancing sludge hydrolysis, achieving sludge pyrolysis-latent growth in the mainstream process.

[0054] Metabolic remodeling mode (long-term, mesophilic, slightly alkaline, with addition of internal carbon source metabolic bacteria): Sludge reduction stems from energy diversion and decoupling. Returning the sludge to the aerobic front end perfectly connects the metabolic links of "PHA anaerobic synthesis" and "PHA aerobic oxidation." The added internal carbon source metabolic bacteria (such as Candidatus Accumulibacter) enhance the synthesis and storage capacity of PHA. Returning ASSR sludge to the aerobic tank is key to activating the synergistic effect of the entire process: it triggers a vigorous oxidative stress reaction, significantly enriching electroactive components such as fulvic acid in EPS (fluorescence intensity increased by ~275%), constructing a highly efficient extracellular electron shuttle network; this allows the intracellularly stored PHA electrons to be efficiently and directionally transported to the functional microbial community, thereby achieving a significant reduction in sludge production (>50%) while driving a significant increase in denitrification and phosphorus removal rates (increasing TN and TP removal rates by approximately 15% and 10% respectively compared to traditional processes), ultimately achieving the dual goals of sludge reduction and deep pollutant removal simultaneously.

[0055] This invention achieves optimal path allocation for "carbon flow" and "electron flow" through intelligent linkage of "mode-parameter-inoculant-path," which is the key to synergistic effect.

[0056] The core of this invention lies in realizing three-dimensional collaborative intelligent control of "mode-parameter-path", which accurately matches the carbon flow path requirements of two completely different reduction mechanisms.

[0057] Latent growth model: Constructing the shortest carbon flow path of "high-speed acid production in the side stream → direct utilization in the anaerobic zone" serves the reduction mechanism of "pyrolysis-latent growth". The addition of hydrolytic bacteria enhances the lysis and hydrolysis processes.

[0058] Metabolic remodeling model: Constructing an efficient electron flow pathway of "lateral flow domestication bacteria → aerobic zone oxidation / shuttle" serves the reduction mechanism of "energy decoupling". The addition of internal carbon source metabolic bacteria (such as Candidatus Accumulibacter) enhances the synthesis and storage capacity of PHA.

[0059] Precise control of the reflux path is the key to unlocking the "last mile" of the above strategy, ensuring that intermediate products (VFA or PHA / fulvic acid) are consumed at the most suitable location and with the highest efficiency, thus globally optimizing the carbon, nitrogen, phosphorus, and energy metabolism network of the system.

[0060] The beneficial effects of this application are as follows:

[0061] This invention employs multi-stage C / N regulation, adopting differentiated strategies based on C / N ranges to achieve broad-spectrum adaptability; it enhances core biological reactions under various modes through a microbial agent dosing system; it achieves optimal carbon flow distribution through reflux path switching; under low-temperature conditions, a heating device is used to enhance hydrolysis or maintain microbial enrichment for different C / N requirements; in low C / N mode, sludge reduction rate >30% and total nitrogen removal rate can be increased by more than 10%; in high C / N mode, sludge reduction rate >50% and total nitrogen and total phosphorus removal rates can be increased by more than 10% respectively; this invention adopts a multi-functional design of a single-sideflow reactor to reduce construction and operation and maintenance costs.

[0062] Specifically, the advantages of this invention are as follows:

[0063] (1) Intelligent and precise control: For the first time, the influent C / N ratio is used as the core control parameter, realizing the linkage and intelligent switching of ASSR "operation mode - process parameters - return path".

[0064] (2) Synergistic effect: By controlling the reflux path precisely, its effectiveness is maximized, achieving sludge reduction and simultaneous nitrogen and phosphorus removal.

[0065] (3) Energy consumption optimization: Path optimization avoids the ineffective consumption of carbon sources and energy, and further reduces the system operating cost through energy-saving mode.

[0066] (4) Broad-spectrum adaptability: It covers the influent range from extremely low to extremely high C / N through three modes and has strong resistance to shock loads. Attached Figure Description

[0067] Figure 1 This is a schematic diagram of the wastewater treatment system of the present invention, wherein 1 is an anaerobic tank, 2 is an anoxic tank, 3 is an aerobic tank, 4 is a secondary sedimentation tank, and 5 is a side-flow anaerobic reactor (ASSR).

[0068] Figure 2 This is a flowchart of the intelligent control logic of the wastewater treatment system of the present invention. Detailed Implementation

[0069] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application. In the following embodiments, the mainstream reactor uses A 2 This applies to O as an example, but it also applies to other processes such as A / O.

[0070] A side-flow wastewater treatment system with adaptive carbon-to-nitrogen ratio, such as Figure 1 As shown, it includes:

[0071] Mainstream A 2 The system includes an O reactor, a side-flow anaerobic reactor (ASSR), an online water quality monitor, an intelligent control unit, a reflux path switching device, and a targeted dosing system for microbial agents.

[0072] The ASSR is equipped with a stirrer, heating rod, pH probe and control valve, sludge inlet and outlet valves for adjusting HRT / SRT, temperature and pH.

[0073] The online monitoring unit detects the COD and TN concentrations of the influent in real time and calculates the C / N ratio.

[0074] The reflux path switching device includes two controllable electric valves and two pipelines, which can transport the ASSR effluent to the front end of the main anaerobic zone or the front end of the aerobic zone.

[0075] The targeted dosing system for the microbial agent includes a storage tank, a metering pump, and a dosing port, as well as Candidatus Accumulibacter bacterial solution concentrate, protease powder, glycosidase powder, and trehalose-kaolin composite protective agent.

[0076] The intelligent control unit receives C / N data from the online monitoring unit and, through a built-in fuzzy PID control algorithm, outputs commands to control the parameters of the ASSR, the start / stop and dosage of the microbial agent dosing system, the opening and closing of the reflux path valves, and the DO setpoint of the main reactor. The intelligent control logic flowchart of the wastewater treatment system of this invention is as follows: Figure 2 As shown.

[0077] Example 1: Treatment of low C / N municipal wastewater using a latent growth model

[0078] Influent C / N ratio < 4.5, COD = 180 mg / L, TN = 60 mg / L. Ambient temperature 20℃.

[0079] The intelligent system activates the latent growth mode: the ASSR parameters are controlled at HRT=6h, T=55℃, and pH=5.5; the bacterial agent system is controlled to add 0.2g / L protease and 0.5g / L Thaurea lyophilized powder to the ASSR; the reflux path valve is controlled to reflux the ASSR effluent back to the front end of the main anaerobic zone; and the DO in the main aerobic zone is controlled at 0.2mg / L.

[0080] Results: Sludge yield decreased to 0.10 g VSS / g COD (reduction rate of 55%), TN removal rate reached 60%, and TP removal rate reached 80%.

[0081] Example 2: Metabolic remodeling mode for treating high C / N wastewater

[0082] Influent C / N ratio > 6, COD = 500 mg / L, TN = 30 mg / L. Ambient temperature 25℃.

[0083] The intelligent system initiates metabolic remodeling mode: ASSR parameters are controlled at SRT = 8 days, T = 30℃, and pH = 7.5; the bacterial agent system adds 10 mg / L to the ASSR. 7 CFU / mL Candidatus Accumulibacter concentrate; control the reflux path valve to reflux the ASSR effluent back to the front end of the main aerobic zone; control the DO in the main anaerobic zone to be 0.1 mg / L and the DO in the aerobic zone to be 2.5 mg / L.

[0084] Results: Sludge yield decreased to 0.06 gVSS / gCOD (reduction rate of 70%), TN removal rate reached 95%, TP removal rate reached 90%, and there was no filamentous bulking.

[0085] Example 3: Treatment of low C / N wastewater under low temperature environment

[0086] Influent C / N ratio < 4.5, COD = 200 mg / L, TN = 65 mg / L. Ambient temperature 10℃.

[0087] The intelligent system detected the low temperature and activated the ASSR insulation device. It also initiated a latent growth mode: controlling ASSR parameters to HRT = 8h, T = 58℃, and pH = 5.8; controlling the addition of 0.3g / L protease to the ASSR via the inoculant system; controlling the reflux path to the anaerobic zone; and controlling the DO in the main aerobic zone to 0.3mg / L.

[0088] Results: The sludge yield decreased to 0.07 gVSS / gCOD (reduction rate of 68%), the TN removal rate reached 65%, and the system operated stably.

[0089] Example 4: Metabolism of low C / N municipal wastewater

[0090] A 2 / O-ASSR and A2 A comparison of the / O wastewater treatment processes shows that with influent C / N < 4.5, COD = 120 mg / L, TN = 30 mg / L, and TP = 3 mg / L, the metabolic remodeling mode is activated, controlling the ASSR parameters at SRT = 6 days and sludge exchange rate at 15%. The effluent from the side-flow anaerobic reactor is returned to the front end of the aerobic tank, resulting in a sludge reduction rate of approximately 10% and a total nitrogen removal rate of 75%. The intelligent system then activates the latent growth mode, controlling the ASSR parameters at HRT = 6–8 h and sludge exchange rate at 50%. The ASSR effluent is then returned to the front end of the main anaerobic zone by controlling the return path valve, resulting in a sludge reduction rate of approximately 30% and a total nitrogen removal rate of 85%, which can improve the total nitrogen removal rate by more than 10%.

[0091] Example 5: Metabolic mode treatment of high C / N wastewater

[0092] Compared with the A / O wastewater treatment process, the A / O-ASSR system had an influent C / N ratio > 8, COD = 250 mg / L, TN = 30 mg / L, and TP = 3 mg / L. In the manual hidden growth mode, the ASSR parameters were controlled at HRT = 6–8 h and sludge exchange rate = 60%. The ASSR effluent was recirculated to the front end of the main anaerobic zone, resulting in a sludge reduction rate of approximately 25%, a total nitrogen removal rate of 80%, and a total phosphorus removal rate of 85%. In the intelligent system, the metabolic remodeling mode was activated, controlling the ASSR parameters at SRT = 6 d and sludge exchange rate = 15%. The recirculation path valve was controlled to recirculate the ASSR effluent to the front end of the main aerobic zone, resulting in a sludge reduction rate of approximately 53%, a total nitrogen removal rate of 95%, and a total phosphorus removal rate of 98%. This improved sludge reduction while increasing the total nitrogen removal rate by 15% and the total phosphorus removal efficiency by 13%.

[0093] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A carbon to nitrogen ratio adaptive side stream sewage treatment system, characterized by, The application relates to a sewage treatment system, which comprises a main flow reactor, a side flow anaerobic reactor, an online monitoring unit, an intelligent control unit, a backflow path switching device and a bacterial agent targeted adding system. The main flow reactor comprises an anaerobic zone, an anoxic zone and an aerobic zone and is integrated with a DO controller. The side flow anaerobic reactor is equipped with HRT or SRT, temperature, pH dynamic adjusting devices and a stirring unit, and is connected with the main flow reactor through a sludge backflow pump. The online monitoring unit is used for detecting the concentrations of influent COD and TN and calculating C / N in real time. The backflow path switching device comprises controllable valves and corresponding conveying pipelines and selectively returns side flow anaerobic reactor effluent to the front end of the anaerobic zone or the aerobic zone of the main flow reactor. The bacterial agent targeted adding system comprises a freeze-dried bacterial agent library, enzymes and a composite protective agent. The intelligent control unit is configured to switch the sewage treatment system among a cryptobiotic growth mode, a metabolic remodeling mode and an energy-saving conservative mode according to the influent C / N detected by the online monitoring unit. In the cryptobiotic growth mode, when the influent C / N is less than 4.5, the hydraulic retention time of the side flow anaerobic reactor is controlled to be 4-12 hours, the temperature is controlled to be 50-60 DEG C, the pH is controlled to be 5.0-6.0, the sludge exchange rate is controlled to be 50-100%, the bacterial agent targeted adding system is controlled to add enzymes to the side flow anaerobic reactor, the effluent of the side flow anaerobic reactor is controlled to backflow to the anaerobic zone of the main flow reactor, and the DO of the aerobic section of the main flow reactor is adjusted to be 0.1-0.5 mg / L. In the metabolic remodeling mode, when the influent C / N is greater than 6, the sludge retention time of the side flow anaerobic reactor is controlled to be 5-15 days, the temperature is controlled to be 25-35 DEG C, the pH is controlled to be 7.0-7.8, the sludge exchange rate is controlled to be 10-50%, the bacterial agent targeted adding system is controlled to add intracarbon metabolic bacteria to the side flow anaerobic reactor, the effluent of the side flow anaerobic reactor is controlled to backflow to the aerobic zone of the main flow reactor, the DO of the anaerobic section of the main flow reactor is adjusted to be 0.1-0.3 mg / L, and the DO of the aerobic section of the main flow reactor is adjusted to be 1.5-3.0 mg / L. In the energy-saving conservative mode, when the influent C / N is 4.5-6, the system defaults to the mild version of the cryptobiotic growth mode, the HRT is controlled to be 6-8 hours, the temperature is maintained at normal temperature or is raised to 30-35 DEG C, the pH is naturally developed to be 6.5-7.0, and the effluent of the side flow anaerobic reactor is controlled to backflow to the anaerobic zone of the main flow reactor. The bacterial agent is protected by a composite protective agent, the activity period of the bacterial agent is greater than or equal to 12 months at normal temperature, the freeze-dried bacterial agent library comprises intracarbon metabolic bacteria, the intracarbon metabolic bacteria are mainly Candidatus Accumulibacter, the composite protective agent is composed of trehalose and nanoscale kaolin at a mass ratio of 1:2, and the enzymes include protease and glycosidase.

2. A carbon to nitrogen ratio self-adapting lateral flow sewage treatment system according to claim 1, wherein, The intelligent control unit is further configured to start the warming device of the side flow anaerobic reactor when the environmental temperature is less than 15 DEG C, the temperature is raised to 50-60 DEG C in the cryptobiotic growth mode, and the temperature is maintained at 25-35 DEG C in the metabolic remodeling mode.

3. A carbon to nitrogen ratio self-adapting lateral flow sewage treatment system according to claim 1, wherein, The application further discloses a sewage treatment method, which comprises the following steps:

4. A method for sludge reduction using the system according to any one of claims 1 to 3, characterized in that, (1) monitoring the influent water quality in real time through the online monitoring unit and calculating the carbon C / N. ​ (2) if C / N is lower than 4.5, the sewage treatment system is controlled to operate in a cryptic growth mode, the bacteria agent targeted dosing system is controlled to add enzymes and / or amino acid metabolizing bacteria to the side-stream anaerobic reactor, and the side-stream anaerobic reactor effluent is backflowed to the anaerobic zone of the main-stream reactor; (3) if C / N is higher than 6, the sewage treatment system is controlled to operate in a metabolic remodeling mode, the bacteria agent targeted dosing system is controlled to add internal carbon source metabolizing bacteria to the side-stream anaerobic reactor, and the side-stream anaerobic reactor effluent is backflowed to the aerobic zone of the main-stream reactor; (4) when 4.5≤C / N≤6, the sewage treatment system is controlled to operate in an energy-saving conservative mode, HRT is controlled to be 6-8 hours, normal temperature or temperature rising to 30-35℃ is maintained, pH is allowed to develop naturally to 6.5-7.0, and the side-stream anaerobic reactor effluent is backflowed to the anaerobic zone of the main-stream reactor.

5. A method of sludge reduction according to claim 4, characterised in that, The method further comprises the step of: when the ambient temperature is <15℃, starting the warming device of the side-stream anaerobic reactor, and rising the temperature to 50-60℃ in the cryptic growth mode and maintaining the temperature at 25-35℃ in the metabolic remodeling mode.

6. A method of sludge reduction according to claim 4, characterised in that, The method further comprises the step of: in the cryptic growth mode, controlling the DO of the aerobic zone of the main-stream reactor to be 0.1-0.5 mg / L; and in the metabolic remodeling mode, controlling the DO of the anaerobic zone of the main-stream reactor to be 0.1-0.3 mg / L and the DO of the aerobic zone to be 1.5-3.0 mg / L.

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